Percent Change Calculator
Calculate percentage change between two values (increase or decrease)
Reliable calculator with instant results. Clean interface, accurate computations.
Formula
((final - initial) / initial) × 100How to Use Percent Change Calculator
- Enter the required values in the input fields.
- Review the formula and methodology used.
- Check the calculated results below.
- Use the results for your specific needs.
Examples
Percentage change measures how far a number has moved from a specific starting point, the right tool for revenue growth, a stock price move, or any before-and-after comparison where one of the two values is clearly the baseline you are measuring against.
The formula
% change = ((new - old) / old) x 100- new
- the later value
- old
- the earlier value, the baseline
Worked example
Quarterly revenue moved from $80,000 to $92,000. Percentage change is ((92000 - 80000) / 80000) x 100 = 15%. Run the same two figures in reverse, from $92,000 down to $80,000, and the change is ((80000 - 92000) / 92000) x 100 = -13.04%, a different magnitude even though the gap between the two numbers is identical, because the denominator has switched.
What trips people up
- Percentage change is not symmetric. Going from 80 to 92 is +15%, but going from 92 back to 80 is -13.04%, not -15%, because each direction divides by a different baseline.
- Use percentage difference instead of percentage change when neither value is clearly the 'before' figure, such as comparing two competitors with no obvious baseline.
- A change from a negative old value produces a result that is easy to misread; check the sign of old before trusting the sign of the answer.
- Change from zero is undefined, since the formula divides by old; a jump from 0 to any positive number is not a percentage change in the mathematical sense, however it gets described informally.
Frequently asked questions
- Why is percentage change not symmetric between two values?
- Because the formula divides by the earlier value, the baseline, and that baseline is different depending on which direction you are measuring, from the smaller number or from the larger one.
- What does a negative percentage change mean?
- The new value is lower than the old one; a change of -13% means the figure has fallen to 87% of where it started, not that it fell by 87%.
- How do I calculate percentage change over multiple periods?
- Chain each period's change onto the previous result rather than averaging the individual percentage changes, since averaging percentages calculated on different bases distorts the true overall change.
- What happens if the old value is zero?
- The formula is undefined, since it divides by old. A rise from zero to any positive number cannot be expressed as a percentage change in the strict mathematical sense.
- When should I use percentage change instead of percentage difference?
- Whenever one of the two numbers is genuinely the starting point you are measuring against, such as last year's revenue against this year's, rather than two independent values being compared side by side.